Thursday, December 25, 2014

Pocket Rifles

In today's post, we will study a particular class of firearm that was very uniquely American and popular from the end of the Civil War to the beginning of World War I. We are going to study about Pocket Rifles, otherwise called Bicycle Rifles.

The origin on these weapons has to do with the Stevens Arms and Tools Company, founded by Joshua Stevens. He was a well-respected toolmaker, who had worked for Colt, Eli Whitney, Smith & Wesson, Allen and many other American gunmakers of the era, before founding his own firearms company in 1864. The company's first two models were a Pocket Pistol and a Vest Pocket Pistol (a year ahead of Remington's Vest Pocket Pistol model). In 1869, the company produced what it called a "Pocket Rifle". This was largely based on their Pocket Pistol model, except that it had a longer barrel, better sights and a cap on the pistol's grip to accept a detachable shoulder stock made of wire. Like the Pocket Pistol, the Pocket Rifle was also a single shot model.

In 1872, a larger 'New Model Pocket Rifle' was added to handle cartridges up to .32 caliber rimfire cartridge. Shortly after that, a line called the 'Hunters Pet Pocket Rifle' was also introduced that went up to .44 caliber. The shoulder stock was also modified so that it slid into a dovetail cut into the butt of the pistol and a screw on the backstrap.

Public domain image of Stevens Pocket Rifles

Click on the image to enlarge. Public domain image.

The New Model Pocket Rifle (First Issue) was the same basic design as the Old Model Pocket Rifle, but was larger and had a heavier barrel to handle the bigger .32 caliber rimfire cartridge. It became far more popular than the old model and outsold it by a wide margin. It was only manufactured for three years though, between 1872-1875, after which it was replaced by the New Model Pocket Rifle (Second Issue) model, which was sold from 1875-1896

The second issue model mounted the firing pin in the frame rather than the hammer, as a safety feature. In 1887, a version that fired the .22 Long Rifle (also known as .22 LR) rimfire cartridge was manufactured for the first time. The .22 LR cartridge was also invented by the Stevens Arms and Tools Company and is still the most popular cartridge in the world today (almost every major firearm manufacturer in the world has made at least one product that fires .22 LR). 

When separated into two pieces (the pocket rifle and the stock), each piece measured between 18 to 24 inches (46-61cm.), which meant they could be stowed in a long coat pocket. Weight of the larger caliber models was around 5 to 5.75 lbs. (2.2 - 2.6 kg.) and the lighter models up to .32 caliber only weighed about 2 - 2.75 lbs. (0.9-1.25 kg.) The barrels were offered in a variety of lengths: 10 inches, 12 inches, 15 inches or 18 inches (25 cm., 30 cm., 38 cm. or 46 cm.)

In the 1880s, advertisements for these guns started to refer to them as "Bicycle Rifles", probably as a marketing tactic to sell them to cyclists of that era, as a light rifle that could be carried for self defense.

An advertisement for a Stevens Bicycle Rifle. Click on the image to enlarge.

They were also offered with carrying cases made of leather or canvas and marketed to hunters as a secondary light rifle, and to fishermen to carry with their fishing equipment.

The nice thing about these compact rifles was that they offered much more range and accuracy than pistols, but were much cheaper than other single shot rifles of that era, while also being much more portable than other rifle models. One Mr. A.C. Gould reported that using a model firing .22 caliber cartridges with an 18 inch barrel, ten shots were placed into a target of 8 inches diameter at 200 yards distance.

After the success of the initial models, other manufacturers also started to make pocket rifles, but Stevens continued to dominate the market until the last model was manufactured during World War I. It must be noted that practically all dealer catalogs of that period that advertised pocket rifles. invariably showed the Stevens brand name. Some larger dealers offered pocket rifles under their own brand, but many of these were actually manufactured by Stevens and marked with the dealer's brand name.

While pocket rifles sold very well in America, they remained a very American invention and never really spread to other countries. While they were light and relatively portable, they were all single-shot models. Their popularity began to decline after semi-automatic and fully-automatic weapons became more common.

Tuesday, December 16, 2014

What's the deal with Barrel Shrouds?

So what is a barrel shroud? It is simply a hollow covering tube that surrounds a barrel (either partially or fully). What does it do? Well, it protects the user of the firearm from accidentally burning himself or herself with the hot barrel.

A typical barrel shroud

A barrel shroud typically has many holes throughout its length. The holes serve to reduce its weight and also dissipate heat by venting out hot air. The next picture shows a barrel shroud attached to a firearm.

As you can see in the above image, the barrel shroud is simply that tube with holes that surrounds the barrel. In the above example, the user has also attached an extra hand grip to the barrel shroud. Since much of the barrel shroud is not in contact with the hot barrel, if the user was to accidentally touch the front of the firearm, the user will not get burned by the barrel.

The curious reader is probably thinking now, "isn't that what the stock of a firearm is designed to do?", Yes, the stock and the receiver do protect the user's hands as well, but they are not considered as barrel shrouds, because they serve other purposes as well, whereas the barrel shroud is a separate component that is screwed on around the barrel and explicitly designed to protect the user's hands (or other body parts) from heat.

Barrel shrouds are generally commonly seen with air-cooled machine guns, but they are also optional components for many semi-automatic models. Some shotguns also feature barrel shrouds. There are many third party component makers that make barrel shrouds for various rifle and shotgun models. In general, they are useful to have with weapons that fire rapidly, because the barrel can heat up quite a bit after a few shots in rapid succession.

If a barrel shroud is simply a covering tube to protect a user from touching a hotter part of the gun, then what's the big deal about them? Well, for a while, barrel shrouds were targets of legislative restrictions in the United States. The now expired Federal Assault Weapons Ban explicitly included barrel shrouds in its list of features for which a semi-automatic firearm could be banned (if a firearm had two features in the list, it could be banned under this law). After the law expired, proposals were made to renew the ban, including this provision, but have not been successful so far.

Amusingly, during an interview on MSNBC in 2007, Representative Carolyn McCarthy was asked about her gun control legislation and why it prohibited people from purchasing firearms that have barrel shrouds and if she even knew what a barrel shroud was. After attempting to avoid the questions twice, she finally admitted, "I don't know what it is, I think it is a shoulder thing that goes up!"

It is amazing that she was trying to introduce a law to ban something without even knowing what it was!

Sunday, December 14, 2014

Forging Rifle Barrel Blanks in the 1920s - II

In our last post, we studied some parts of a factory designed to produce rifle barrel blanks. In today's post, we will continue studying the process. As noted before, some of the details come from a book, "The Working of Steel" by Fred Colvin and K.A. Juthe, and in addition, K.A. Juthe was the designer of the factory as well.

Where we last left off, the barrel blanks were straightened out and tested for straightness. The next process was to heat treat the barrel blanks and increase their hardness. We will discuss this heat treating process shortly.

The last process was to grind the ends of each blank and then grind a spot on the enlarged end of each blank and test the hardness of the blank on a Brinell machine, to ensure that the blanks met the required hardness nunbers

The Brinell hardness test was invented by Swedish engineer Johan Brinell in 1900. It was one of the first standardized hardness tests used in engineering and is still used today. The test is very simple. It uses a steel or tungsten carbide ball of diameter 10 mm. (0.39 inches), which is used as an indenter. The ball is placed on the surface of the object to be tested and a 3000 kg. (or 6600 lbf.) test force is applied to the ball for a specific time (normally 10 to 15 seconds). After this, the ball is removed and it leaves a round indentation on the surface of the object. The diameter of this indentation is measured and the Brinell Hardness Number (BHN) is calculated, based upon the diameter of the ball, diameter of the indentation and the force applied to the ball. For softer materials, such as aluminum, a smaller test force (e.g. 500 kg. (or 1100 lbf.) is used instead.

The above image shows a line drawing of the concept and the formula actually used to calculate the Brinell Hardness Number (HB in the image above).

Returning back to our study of the factory process, the barrel blanks were tested for hardness to make sure that they had a Brinell Hardness Number (BHN) of at least 240.

At this point, the barrel blanks were shipped off to a barrel manufacturer, who would then drill, ream, finish-turn and rifle the blanks into complete barrels.

Now. all through the description of the process so far, we've been talking about heating the blanks for various purposes. We will cover the heat treatments in detail here. There were actually four separate heat treatments done to the blanks.

  1. Heating and soaking the steel above the critical temperature and quenching it in oil, to harden the steel through to the center of the blanks.
  2. Reheating the steel for drawing of temper  for the purpose of meeting the physical specifications of the blank
  3. Reheating the blanks to meet the machineability test for production purposes
  4. Reheating to straighten out the blanks when hot.
We will study each of the four heating processes in detail. 

For the first heating process, the blanks were slowly brought up to the required heat, which is about 150 degrees Fahrenheit (65.5 degrees centigrade) above the critical temperature of the steel. The blanks were then soaked at a high heat for about one hour before quenching in oil. The purpose of this treatment was to eliminate any strains already existing in the bars that may have been put there from milling operations done to the bars. Remember that steel is an elastic substance and working it puts stress on the bars. For instance, during the production of steel, the manufacturer rolls the bars through various rollers to make them the required diameter, which causes the bars to come out stressed. The heat treatment process removed the stress caused by rolling, hammering, cutting etc. It also ensured that the heat treatment applied to the entire cross-section of the bar and not just the surface. In addition, if a blank had seams or slight flaws, these opened up drastically during the quenching process and made it easy to determine if a blank was defective or not.

The oil used for quenching was kept at a temperature of  around 100 degrees fahrenheit (38 degrees centigrade). This is an ideal temperature is to prevent shock to the steel when it is dropped into the quenching oil, otherwise it could develop surface cracks on the piece.

The second heating process (the one for drawing the temper of the steel) was a very critical operation and had to be done carefully. The steel had to be kept heated within 10 degrees of temperature fluctuation in the process. The degree of heat necessary for this operation depended entirely on analyzing the steel. Even if the steel was purchased from the same manufacturer, there was always some variation in different batches received from the manufacturer.

The third heating process (reheating for machineability) was done at a temperature of around 100 degrees Fahrenheit (38 degrees centigrade) less than the drawing temperature used for the second heating process. However, the time of soaking was almost double that of the second process.

For both the second and third heating process, after the heating was done. the blanks were buried in lime so that they would be out of contact with air, until their temperature had dropped down to room temperature.

The fourth heating process was used when straightening the blanks. In this process, the blanks were first heated to about 900-1000 degrees Fahrenheit (482-538 degrees centigrade) in an automatic furnace for 2 hours before straightening them. The purpose of heating before the straightening was to prevent any stresses being put into the blanks during the straightening operation. This is necessary because when later processes such as drilling, turning and rifling are done to the blanks, they have a tendency to spring back into the shape they were in when they left the quenching bath. By heating before straightening, the blanks are prevented from doing this.

Another method was later found to produce an even better barrel blank. The blanks were first rough-turned to the final barrel diameter and then heated to about 1000 degrees Fahrenheit (538 degrees centigrade) for about 4 hours before sending them to the barrel manufacturer. Blanks produced with this method remained practically straight during the different barrel making operations (drilling, reaming, finish-turning and rifling). This meant that the barrel manufacturers didn't need to straighten barrels after they were finished (which was a much more expensive operation). This method was tested out with one of the largest barrel manufacturers in the US and it proved to be very effective.

As the reader might be wondering, all this heat-treating needed a large amount of oil for cooling and one of the problems was how to keep all this oil at the proper temperature. After much study, a cooling system was developed for the factory. The next two images show the cooling system as seen on the roof from the outside of the factory.

Click on the images to enlarge. Public domain images.

The next image shows the details of the cooling system:

The hot oil is pumped up from the quenching tanks through the pipe A into the tank B, From here, the oil runs down onto the separators C, which break the oil up into fine particles, that are blown upwards by the fans D. The spray of oil particles is blown up into the cooling tower E, which contains banks of cooling pipes and baffles F. Cold water is pumped through the inside of the pipes. The spray of oil particles collects on the outside of the cold pipes and forms larger drops, which fall downwards onto the curved plates G and then run back to the oil-storage tank below ground. The water pumped through the cooling pipes comes from 10 natural artesian wells at a rate of 60 gallons per minute and this serves to cool about 90 gallons of oil per minute, lowering it from a temperature of about 130-140 degrees Fahrenheit to about 100 degrees Fahrenheit. The water comes out of the wells at an average temperature of 52 degrees Fahrenheit. The pump is driven by a 7.5 HP motor and the speed can be varied to suit the amount of oil to be cooled. The plant was designed to handle up to 300 gallons of oil per minute.

The finished blanks from this factory were sent to different barrel manufacturers to drill, ream, rifle etc. to their requirements.

Tuesday, December 9, 2014

Forging Rifle Barrel Blanks in the 1920s - I

After all the stuff we studied about metallurgy in the last several posts, we will look at an ancillary subject today, forging of rifle barrel blanks. We have already covered barrel manufacture from barrel blanks in some detail in previous posts many months ago. In today's post, we will study the process of manufacturing the barrel blanks as it was done in a factory in America in the 1920s. In particular, this was a factory belonging to Wheelock, Lovejoy & Company, which was designed to mass-produce rifle barrels designed to meet specifications demanded by some foreign governments. Some of the pictures and information in this post was taken from the book "The Working of Steel" by Fred Colvin and K.A. Juthe, and in addition, K.A. Juthe was the designer of the factory as well.

This factory did not manufacture its own steel: instead, they bought what they needed from a large steel manufacturer. The steel manufacturer made the steel to the required specifications and supplied them in the form of bar stock, but the length of the supplied bars was longer, typically each bar measured something like 30 or 35 feet long (about 9.1 to 10.7 meters long).

Cutting the bar stock to size.

Therefore, the first step in the process was to cut each steel bar into smaller lengths to make barrels. The bars came on trucks and were fed through the cutting-off shear, where they were cut into pieces of the proper length. The pieces were actually a little longer than the final barrel lengths, to allow for trimming during the machining process.

A close up of the details of the cutting off is shown in the next image.

A is the stock stop bolted to the side of the frame and the ledge formed by the strip bolted to the stop, keeps the bar stock level during the cutting process. The hold-down B prevents the back end of the steel bar from flying up when the bar is cut. The knife C has several notched edges with which the barrels can be cut, so that it need not be taken out for resharpening, until all the notches are dull.

The cut barrel pieces then passed into the next room, where there was a forging or upsetting press.

Upsetting (or more properly, upset forging) is a process of increasing the diameter of the end of a work piece, by compressing it along its length inside a die. The images below show the process.

The barrel pieces were heated in a furnace to soften them, before being sent through the upsetting press. The press could handle the barrels from all the heating furnaces shown in the room. The men changed work at frequent intervals, to avoid excessive fatigue.

The barrels were then sent through a continuous heating furnace to be reheated and then straightened out as much as possible before being tested for straightness.

A Continuous Heating Furnace

In the above machine, each barrel was tested for straightness by placing it on the rollers as shown in the image above. The screw on the press was used to apply pressure and straighten out the barrel as needed.

We will continue our study of the process in the next post or two.

Thursday, December 4, 2014

Questionable Tactics

After that long series about different metals used in firearms manufacturing, might as well take a break from a dry topic and watch something else instead.

Initially, your humble editor thought that someone was parodying the infamous Rex Kwon Do scene from the movie Napoleon Dynamite. (In case you haven't seen the movie, here's clip 1 and clip 2). Unfortunately, what you're about to see is not a joke, there is actually someone trying to train people to use tactics like this. This group is called the "Sulsa Do Corps" (no joke, that's what they call themselves). See for yourself:

This video was originally posted at a youtube channel called God Rock Ministries / Expert Karate, which appears to be some sort of combination of church and karate school (dojo). This school appears to be run by a Mr. David Bateman. They removed the original video from the channel, when word about its unintentional comedy started to spread. Unfortunately for them, the video was saved by someone else and here it is :).

It is a darn good thing they are using pellet guns with no ammunition, instead of real pistols. Questionable tactics? Where do we start. First, we have quite a few instances of them sweeping each other with the muzzles of their pistols (big safety no-no). Then, we have fingers placed on the trigger at all times (bad idea). Next we have a couple of cases of shooting at the ceiling and open door, while moving and rolling around (another safety no-no). What's with the backwards dive to the ground anyway and since when is running backwards without looking at where you're going ever a good idea. Then, we have firing the pistols close to own face/someone else's face (if those were real pistols, guess whose eardrums are getting blasted to hell, not to mention hot cartridge brass getting ejected on someone else). We also have thumbs placed behind the slide in some instances (if that was a real pistol, someone is going to have a broken thumb when the slide moves backwards at high speed after the cartridge is fired). Then, they run in front of each other, with the ones in the back shooting (good chance of getting shot in the back if they were using real pistols). Then, there's the firing between the legs position (guess whose kneecap is going to receive some hot cartridge brass if those were real pistols). Firearm sights are there for a reason, but they don't seem to know how to use them. We even have a few instances of triggers pulled when one of the others was in the line of fire. The funniest part in your humble editor's opinion is around 0:13 of the video, when the gentleman starts his solo run backwards, holds his pistol practically next to his cheek, then shoots one through the open door, then falls over backwards and bangs his head against the wall! There's probably a few more bad things I missed because I was laughing too hard.

The scary part is that they appear to be dead serious and actually imagine that this is good training. If those were real pistols, someone is definitely going to get hurt or worse. In case you're wondering, this David Bateman has a few more videos about his martial arts training academy, including this gem:

Yep, seems he's the second coming of Rex Kwon Do himself.


Tuesday, December 2, 2014

Metals Used in Firearms - XIX

In our last post, we looked at a modern method of manufacturing steel, Basic Oxygen Steelmaking (a.k.a) the BOS process. As we saw, this is based on the Bessemer process, except that we use oxygen instead of air to burn off impurities. When we studied the Bessemer process, shortly after that, we studied how fluid compressed steel was made from steel made by the Bessemer process. The purpose of compressing the steel was to eliminate gas bubbles and hairline cracks in the ingot. Well, the BOS process also could have these problems for the same reasons as well, so we will study how these problems are tackled in today's post.

The problem is that when steel is manufactured using the BOS process, oxygen is injected over the molten metal to burn off impurities. As it turns out, not all of this oxygen gets used up to burn impurities, some of the excess oxygen gets dissolved in the molten steel as well. When the metal solidifies, this oxygen is released out and can do bad things to the steel. For one, it can combine with the iron in the steel, to form iron oxide (i.e. rust). The second is that the oxygen gas can form gas bubbles (blowholes) in the ingot. Thirdly, it can combine with the carbon in the steel, forming carbon monoxide and carbon dioxide, which reduces the carbon content of the steel and weakens it. Also, the carbon monoxide and carbon dioxide gas can form blowholes in the steel as well. Gas bubbles and blowholes cause the steel to have pores in it. One more problem is that the carbon monoxide tends to form more on the outside of the ingot and escapes out. This causes non-uniform distribution of the carbon in the steel, because the outside of the ingot now becomes relatively pure iron, while the inside of the ingot is carbon steel. Also, steel shrinks considerably as it cools and trapped gas in the metal can cause gaps and hairline cracks in the ingot as well. For firearm applications, the presence of rust, bubbles, cracks and pores is undesirable, as is the non-uniform distribution of carbon in the steel.

So clearly, we must minimize the oxygen in the molten steel before it solidifies and preferably remove it without forming a gas like carbon monoxide, because the gas could cause bubbles and cracks to form. In modern times, this is done right after the molten steel is tapped out of the BOS furnace and poured into molds, by adding deoxydizing agents to the molten steel. Basically, a deoxydizing agent is a chemical that strongly combines with oxygen better than carbon and iron do. Therefore, as the molten steel cools, the dissolved oxygen combines with the deoxydizing agents first, before it has a chance to react with the iron or carbon in the steel. A good deoxydizing agent also forms solid slag rather than a gas, so that there are no gas bubbles or cracks formed as the steel cools. Such a steel is called "Killed Steel".

Typical deoxydizing agents are aluminum, ferrosilicon (an alloy of iron and silicon) or ferromanganese (an alloy of iron and manganese). These combine with the oxygen dissolved in the molten steel to form aluminum oxide (alumina) or silicon dioxide (silica). Deoxydizing agents are added as soon as the steel is poured out from the furnace into molds and may be added individually or together, depending on the type of steel desired.

As the molten killed steel hardens in the mold, there are practically no gas bubbles seen, because most of the dissolved oxygen has been removed by the deoxydizing agents. Since there are no bubbles formed, the steel quietly solidifies in the mold and this is why it is called "killed steel". The ingot is generally free from blowholes and the distribution of carbon and other alloying elements in the steel is more uniform. This ensures that the killed steel ingot has excellent chemical and mechanical properties that are uniform throughout the entire length of the ingot. Killed steel ingots are sometimes marked with the letter "K", to indicate how they were manufactured.

Not all steel manufactured is killed, but any steel with carbon content greater than 0.25%, or in general, any steel that is meant to be forged later, is killed, Stainless steel and alloy steels are also killed as part of their manufacturing process. As we saw earlier in the series, 4140 and 4150 steels that are used in firearms have 0.40% or 0.50% carbon content. Stainless steel is also used in the firearms industry.